Does the "Warhead" project change the stance for the mod being built on Crysis 1, or does it simply mean you will migrate it to the new game-tech once its available?
MechWarrior: Living Legends is a modification for Crysis, not Crysis: Warhead.
There are no plans to switch engines or migrate to future Crytek releases at this point.
As far as I know the Crysis Warhead engine will be forward and backwards compatable.
I THINK they are doing the basic engine updates from Warhead into standard Crysis as well. Atleast I hope so.